1. Field of the Invention
The present invention relates to a honeycomb catalyst body. More particularly, it relates to a honeycomb catalyst body which can be contained even in a limited space and which has high mechanical strength, small pressure loss, and suitable purification performance.
2. Description of Related Art
It has been demanded that harmful substances such as NOx in exhaust gases discharged from internal combustion engines such as a car engine, a construction machine engine and an industrial machine stationary engine, the other burning devices and the like are purified and then discharged, in consideration of influences on the environment. Therefore, to purify the harmful substances, there has been used an exhaust gas purifying device including a plurality of honeycomb catalyst bodies each having a constitution in which a catalyst is loaded onto a honeycomb structure as a loading body.
As each honeycomb catalyst body, for example, there is known a honeycomb catalyst body including partition walls which define and form a plurality of cells to become through channels of a fluid and onto which a predetermined catalyst is loaded. Moreover, when the honeycomb catalyst body is used, the catalyst comes in contact with an exhaust gas in a case where the exhaust gas flows through the cells of the honeycomb catalyst body, so that the harmful substances in the exhaust gas can be purified.
Examples of the honeycomb catalyst body include a honeycomb catalyst body loaded with a selective reduction catalyst (SCR), a honeycomb catalyst body loaded with an ammonia slip preventing catalyst (ASC), and a honeycomb catalyst body loaded with a three-way catalyst and the like. In the above exhaust gas purifying device, these honeycomb catalyst bodies are suitably selected and arranged in series. Specifically, an exhaust gas purifying device is known in which a first catalyst body loaded with a lean NOx adsorber catalyst or the three-way catalyst is disposed on an upstream side, and a second catalyst body loaded with the selective reduction catalyst is disposed on a downstream side of the first catalyst body (e.g., see Patent Document 1). In this exhaust gas purifying device, when an air-fuel ratio of an engine is rich and specifically about 14.0, ammonia is generated from NOx and H2 in the exhaust gas by use of the first catalyst body. Afterward, NOx in the exhaust gas can be reduced and detoxified in the second catalyst body by use of the generated ammonia.    [Patent Document 1] JP-A-2011-149360